People walk past the logo for the upcoming Super Bowl XLIX between the Seattle Seahawks and New England Patriots on January 28, 2015 in Phoenix, Arizona
Phoenix (AFP) - Health authorities in Arizona are on alert after warning that 1,000 people may have been exposed to a measles outbreak as the US state prepares to host this weekend's Super Bowl.
Arizona's Department of Health recommended that any unvaccinated child or adult who had been in contact with infected people to spend 21 days in isolation at home to curb the risk of spreading the virus.
Anyone deemed at risk of infection has been offered doses of immune globulin, which would not prevent them from getting measles but can reduce symptoms if administered within six days, authorities said.
Measles is highly contagious and can be spread through the air without physical contact. Infection usually begins with a fever, followed by a cough, runny nose, conjunctivitis and a rash.
Complications from measles can include blindness, hearing loss, pneumonia and death. One to three children of every 1,000 infected with measles will die from it, according to the US Centers for Disease Control and Prevention.
"This is a critical point in this outbreak," Arizona Department of Health Services Director Will Humble said in a statement.
"If the public health system and medical community are able to identify every single susceptible case and get them into isolation, we have a chance of stopping this outbreak here."
Humble said more than 1,000 people were believed to have come into some contact with seven measles cases confirmed in Arizona so far.
- Disney outbreak -
The latest outbreak has centered around the Disneyland theme park in Anaheim outside Los Angeles, and has grown to 84 confirmed cases in 14 states, 67 of which are known to be linked to the Disney outbreak, the US Centers for Disease Control said Thursday.
Four of the patients diagnosed in Arizona are members of one unvaccinated family who visited the California resort.
The Arizona warnings come as the state's capital Phoenix welcomes visitors for this weekend's finale to the American football season, the Super Bowl, between the Seattle Seahawks and New England Patriots.
Sunday's showpiece -- the biggest event on the American sporting calendar -- is the climax of a week-long jamboree whose epicenter is a swathe of downtown Phoenix dubbed Super Bowl Central featuring exhibits, beer gardens, free concerts and nightly firework shows.
Local media reports estimate that a million visitors, many of them from out of state, will throng the complex of attractions this week.
The United States declared measles eradicated in 2000 -- meaning it is no longer native to the United States -- though the world sees about 20 million cases each year.
There were 644 cases of the disease in the US last year -- a big jump from 173 cases in 2013.
The spike coincides with an anti-vaccination trend that has emerged in recent years, particularly in North America.
Opponents fear the MMR (measles, mumps, rubella) vaccine causes autism, even though an array of studies have ruled out any link.
"It is frustrating that some people have opted out of vaccination," said Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases.
January's 84 US cases exceeded the typical 60 or so seen each year in the United States over the past decade, she added.
Babies, people with cancer and certain immune deficiencies are unable to get vaccinated and rely on those around them for protection, a principle known as herd immunity.
Schuchat urged people to get the vaccine for their children, and if adults are unsure about their own immunity, they should get the MMR vaccine themselves.